The present invention relates to a case structure of a mobile phone, and more particularly to a case structure of a mobile phone providing improved shielding effectiveness.
Electromagnetic Interference (EMI) is a common and well-known problem associated with electronic equipment. EMI concerns are present in the design of mobile phones. Shielding mobile phones from EMI is essential for optimum signal integrity and communication clarity. U.S. Pat. No. 5,271,056 disclosed a mobile phone having means for protecting components on a printed circuit board (PCB) thereof from EMI, as shown in FIG. 4 of the present application. The mobile phone has a main body (not shown) and a PCB 50 (shown rear side up). A rear side of the PCB is covered by ground foil 501, as is an edge of a front side. A frame plate 60 of conductive metal or metal-coated plastic comprises a flat plate 601 and a raised edge 602 around a perimeter of and bisecting the flat plate 601. The PCB 50 is secured to the frame plate 60 by means of screws 70. The ground foil 501, which at the edge of the PCB 50 is connected to a strip in the component side of the board 50, will together with the raised edge 602 and the plate 601 form a shielding means for shielding electronic components on the PCB facing the plate 601.
The disadvantages of the prior art mobile phone are that it needs an additional metal frame plate 60 and a plurality of screws which are used for securing the PCB 50 to the frame plate 60, thus increasing manufacturing cost and consuming space. Further, it is laborious to assemble the EMI shielding means. Hence, an improved mobile phone having an EMI shield is required to overcome the disadvantages of the prior art.
A main object of the present invention is to provide a case for a mobile phone, and more particularly to provide a case which includes an improved EMI shield for a mobile phone.
The present invention comprises a front case, a PCB, a conductive elastic member and a rear case. The front and the rear case are made of a conductive metal material. The front case includes a keyboard and a display. The PCB is disposed between the front case and the rear case and has ground traces and electronic components thereon which face the rear case. The rear case includes a bottom, a surrounding sidewall and a cavity defined between the bottom and the surrounding sidewall. The bottom forms rails forwardly extending into the cavity. The rails have a shape in conformity with and aligning with the ground traces of the PCB when the PCB is secured in the rear case. A conductive elastic member is formed on the rails and directly electrically connects the ground traces of the PCB. The front case, the rear case, the rails, the elastic member and the PCB together form an EMI-shielding means for shielding the components of the PCB from EMI.